The long range goal of this research is a better understanding of the basic mechanism of iron metabolism, which would, in turn, lead to a better understanding of metabolic disorders, such as iron deficiency anemia or abnormal increase of body iron known as hemochromatosis. In particular, this research would attempt to assess the importance of a newly discovered and structurally complex copper-containing enzyme (ferroxidase-II) of animal sera in the mobilization of iron from storage tissues and in the intestinal absorption of iron from dietary sources. Ferroxidase-II, which has been purified and thoroughly characterized, from various animal sera, will be injected into the blood stream of copper-deficient animals to test its in vivo capability for mobilizing iron from tissue stores and to assess its importance in this process compared to ceruloplasmin (ferroxidase-I). Further more, the possibility that ferroxidase-II may be the source of the ferroxidase activity recently detected in the intestinal mucosa will be investigated. The isolation, purification, characterization, and positive identification of the source of this intestinal ferroxidase activity will be attempted. If, indeed, the ferroxidase component of the mucosal cell were identified as ferroxidase-II, this would suggest that a second and possibly primary physiological role of this enzyme may be in the intestinal processing of dietary iron. The establishment of a role for ferroxidase-II in the in vivo mobilization of iron or in the intestinal absorption of iron would provide considerable further evidence that the copper-containing ferroxidases are the much sought after "missing link" between copper and iron metabolism.